1. Field of the Invention
This invention relates to a sliding bearing, namely, a pad bearing or centering bearing for a one-way clutch to be used for torque transmission, back stop or overrunning in or automobile automatic variable speed device, and more particularly to a centering block for leading lubricating oil to a clutch member, e.g., sprag or roller.
2. Related Background Art
FIGS. 10 and 11 show a conventional one-way clutch. In FIG. 10, the one-way clutch includes an inner ring 1, an outer ring 2, and rollers 3 interposed between these rings. Cam surfaces such as illustrative cam surface 2a are formed at the inner peripheral surface of outer ring 2 to form cam structures with rollers 3 so as to allow rotation of inner ring 1 relative to outer ring 2 in only one direction. Inner ring 1 freely runs relative to outer ring 2 in arrow direction A. In FIG. 11, at one side surface of outer ring 2, a step 2b is formed, and a first side plate 4 is mounted on step 2b, centering the side plate 4. First side plate 4 covers first end surfaces of rollers 3, and parts of the plate 4 are folded to form folded pieces 4a, which penetrate between the inner and outer rings.
A front end portion 4b of each piece 4a projects out from the other side. At the other side of outer ring 2, a second side plate 5 covering the other end surfaces of rollers 3 is arranged. Second side plate 5 has small holes 5a through which the folded pieces 4a project and front end portions 4b of the pieces 4a are caulked at the outer surface of second side plate 5 so as to center second side plate 5 and to fix both side plates 4 and 5 to outer ring 2.
Between outer ring 2 and inner ring 1, a centering block 6 is disposed. This centering block 6 has a sliding part 6a slidingly contacting with inner ring 1, folded portions 6b engaging with a recess 2c in the inner peripheral surface of outer ring 2 and supported by corresponding folded pieces 4a, and supporting portions 6c connecting sliding portion 6a and folded portions 6b. The folded portions 6b are supported by the folded pieces 4a so that the centering block 6 is fixed to recess 2c of outer ring 2.
Inner ring 1 has a lubricating hole 1a for feeding lubricating oil. The hole la penetrates from the outer peripheral surface to the inner peripheral surface of the ring. Inner ring 1 has a groove 1b at its inner peripheral surface and lubricating oil is received in groove 1b for supply of the oil to rollers 3 through lubricating hole la by centrifugal force. The one-way clutch is, as shown in FIG. 12, fixed to a plate 100 by welding.
According to the conventional one-way clutch, the lubricating oil hole is provided to supply lubricating oil to the rollers or sprags. However, this hole produces stress concentration which causes damage and reduces service life, and the working of this hole is complex, resulting in high cost. In addition, the one-way clutch becomes heavy and bulky, which is also disadvantageous. Further, the lubricating oil supplied to the one-way clutch from the conventional lubricating oil hole is, as shown in FIG. 13, discharged out of the one-way clutch as the flow of the oil is blocked by the centering block, and this requires a large amount of lubricating oil.